Blood Supply to the Brain

Question 1

What is different about arteries in the brain?

Answer 1

Thin-walled so are easily blocked or ruptured

Question 2

What is different about veins in the brain?

Answer 2

Have no valves, are thin-walled and have no muscles or elasticity

Question 3

What does the internal carotid artery terminate as?

Answer 3

The anterior cerebral and middle cerebral arteries

Question 4

What connects the two anterior cerebral arteries?

Answer 4

Anterior communicating arteries

Question 5

What are the 4 main branches of the internal carotid artery?

Answer 5

Ophthalmic, posterior communicating, middle cerebral and anterior cerebral arteries

Question 6

What does the ophthalmic artery supply?

Answer 6

Goes to the orbit and retina and also connects to the external carotid artery

Question 7

What is the role of the posterior communicating artery?

Answer 7

Connects the carotid and vertebral artery systems (anterior and posterior circulation)

Question 8

What is the role of the middle cerebral artery?

Answer 8

Supplies the basal ganglia, internal capsule and lateral 2/3rds of the cortex

Question 9

What is the role of the anterior cerebral artery

Answer 9

Supplies the internal capsule, medial side of frontal and parietal lobes and anastomoses with the middle cerebral artery

Question 10

Describe the passage of the vertebral arteries

Answer 10

Ascend through transverse foramina of C1-6 vertebrae and enter the cranium via the foramen magnum and unite with the contralateral vertebral arteries at the posterior pons to form the basilar artery

Question 11

What forms the posterior circulation to the brain?

Answer 11

Vertebral arteries, basilar artery and posterior cerebral artery

Question 12

What do the vertebral arteries supply?

Answer 12

Spinal cord and the dorsal medulla of the brainstem (via the PICA branch)

Question 13

What does the basilar artery supply?

Answer 13

Pons and cerebellum

Question 14

What does the posterior cerebral artery supply?

Answer 14

The inferior and medial aspects of the temporal and occipital cortex as well as the thalamus, midbrain and posterior internal capsule and anastomoses with the middle cerebral artery

Question 15

What is the Circle of Willis?

Answer 15

Circle of cerebral arteries composed of: anterior communicating artery, anterior cerebral arteries, internal carotid arteries, posterior communicating arteries and posterior cerebral arteries

Question 16

Which areas of the brain are supplied by the anterior cerebral artery?

Answer 16

Medial and superior brain as well as the frontal pole

Question 17

Which areas of the brain and supplied by the middle cerebral artery?

Answer 17

Lateral brain and temporal pole

Question 18

Which areas of the brain are supplied by the posterior cerebral artery?

Answer 18

Inferior brain and occipital pole

Question 19

Where do all venous sinuses drain?

Answer 19

Internal jugular vein

Question 20

Describe the venous drainage of the brain

Answer 20

Superficial cerebral veins cross the subarachnoid space and pierce the dura

Question 21

What is the function of arachnoid granulation?

Answer 21

Allow CSF to flow into venous blood of the sinuses but prevent the backflow of blood into the sub-arachnoid space

Question 22

What is the cavernous sinus?

Answer 22

A large collection of thin-walled veins and it is the only place where an artery travels through a venous structure.

Question 23

What is the main blood supply to the spinal cord?

Answer 23

Great segmental medullary artery (Artery of Adamkiewicz)

Question 24

What are the risk factors for stroke?

Answer 24

Atherosclerosis, hypertension, aneurysm, age, head injury, alcoholism, atriovenous malformation

Question 25

What happens if there is damage to the middle cerebral artery in the dominant hemisphere?

Answer 25

Dominant hemisphere is often the left side (in right-handed people) and therefore there would be global aphasia (loss of speaking functionality) and sensorimotor loss on contralateral face, upper limb and trunk

Question 26

What happens if there is damage to the middle cerebral artery in the non-dominant hemisphere?

Answer 26

Causes neglect syndrome, where they can no longer perceive information inputting on one side of their body

Question 27

What happens if there is damage to the anterior cerebral artery?

Answer 27

Contralateral sensorimotor loss below the waist, urinary incontinence, personality deficits and ‘split-brain syndrome’ where there is difficulty conveying information across hemispheres due to inability to cross the corpus callosum

Question 28

What happens if there is damage to the posterior cerebral artery?

Answer 28

Contralateral homonymous hemianopia, reading and writing deficits and impaired memory

Question 29

What is lateral medullary syndrome?

Answer 29

Affects the posterior inferior cerebellar artery and there is sudden onset of symptoms including: nausea, dysphonia (hoarse voice), contralateral loss of pain and temperature sensation in body, ipsilateral loss of pain and temperature in the face, loss of gag reflex and presence of ipsilateral Horner syndrome

Question 30

What are TIAs?

Answer 30

Transient ischaemic attacks which involved a temporary loss of brain function (less than 30 minutes) which has a sudden onset but is resolved within 24 hours

Question 31

What are the branches of the external carotid artery?

Answer 31

• Superior thyroid
• Ascending pharyngeal
• Lingual
• Facial
• Occipital
• Posterior auricular
• Superficial Temporal
• Maxillary

Question 32

Where does the common carotid artery bifurcate?

Answer 32

Splits into external and internal at the level of the superior border of thyroid